1. Field of the Invention
The present invention relates to a method for operating ion exchange equipment, and ion exchange equipment.
2. Description of Related Art
In water softening apparatuses, which are ordinary ion exchange equipment, co-current regeneration is adopted in many cases since the structure therefor is simple. However, according to co-current regeneration, the level of hardness leak is relatively high in a water treating process (water-softening process); thus, in a boiler or other instruments wherein treated water is used, a scale trouble is easily caused. For this reason, in order to obtain treated water having a high purity, it is necessary to make the regeneration level (use amount of a regenerant per liter of an ion exchange resin) thereof high.
Counter-current regeneration makes it possible to solve a problem of a decrease in the purity of treated water since the regeneration gives a lower hardness leak level than co-current regeneration. However, in order that an apparatus therefor can hold an ion exchange resin bed so as to cause resin beads not to flow in a regeneration process, various complicated techniques are required.
On the other hand, split-flow regeneration disclosed in Patent document 1 (WO 07/23796) and Patent document 2 (JP-A-2008-55392) can solve the problems of co-current regeneration and counter-current regeneration simultaneously. In other words, this method has an advantage that even when the regeneration level is restrained into a low level, treated water having a high purity can be obtained within the range of a practical water collection amount.
In order to solve problems of co-current regeneration and counter-current regeneration, the inventors have been developing water softening apparatus of a split-flow regeneration type. In the process of the development, the inventors have then found out a new problem of split-flow regeneration.
The new problem is caused in a case where with an increase in the size of water softening apparatus the inside diameter of their resin storage tank is increased. In other words, as a ratio of the depth D1 of their ion exchange resin bed to the diameter Z thereof is made smaller, there is caused a phenomenon that a desired water collection amount is not obtained. This phenomenon becomes more remarkable as the ratio of D1/Z is made smaller.